1. Field of the Invention
The present invention relates to a heat pump apparatus using gas or solar heat as the heat source to obtain a chilled water or cooling air and, more particularly, to an absorption heat pump using a medium that operates primarily at atmospheric pressure or above.
2. Description of the Prior Art
In FIG. 6, an example of conventional absorption heat pump apparatus 200 is shown. The rich solution, with a high refrigerant concentration, which is pressurized by the solution pump 201 recovers the absorption heat from the heat absorber 202, and then the solution temperature rises. At the solution heat exchanger 203, the temperature of the concentrated rich solution further rises by the sensible heat of the poor solution, which is low refrigerant concentration flowing from the rectifier 205. The rich solution then flows into the generator 204, and is externally heated.
The rich solution thus heated through the absorber 202, solution heat exchanger 203, and generator 204 produces refrigerant vapor at the generator 204. The rich solution in vapor-liquid two phase state flows into the rectifier 205. The rectifier 205 separates the vapor and liquid, outputs the refrigerant vapor to the condenser 206, and returns the poor solution having a reduced refrigerant content to the solution heat exchanger 203. The function of the rectifier 205 is to liquefy the vapor of the medium contained in the refrigerant vapor to supply high purity refrigerant vapor to the condenser 206.
As described above, the sensible heat extracted from the poor solution flowing out from the rectifier 205 is applied to the rich solution, thus lowering the temperature of the poor solution supplied to the absorber 202. The high purity refrigerant vapor produced by the rectifier 205 flows out to the condenser 206, and the heat is externally discharged to liquefy the vapor. Thereafter, the pressure is reduced by the expansion valve 207, cooling the fluid which then flows into the evaporator 208. The evaporator 208 takes heat from the outside of the heat pump system to evaporate the solution, and returns the poor solution to the absorber 2.
In general, a pre-cooler 209 is provided in the solution paths between the condenser 206 and the expansion valve and between the evaporator 208 and the absorber 202. The pre-cooler 209 exchanges heat between the low temperature refrigerant vapor from the evaporator 208 and the high temperature fluid refrigerant from the condenser 206 in order to increase the cooling effect of the evaporator 208. The refrigerant vapor that passes the pre-cooler 209 returns to the absorber 202. In the absorber 202, the refrigerant vapor is absorbed into the poor solution returning from the solution heat exchanger 203, part of the absorption heat generated in this process is applied to the rich solution, and the remaining heat is vented outside the system. With the absorption heat pump apparatus thus described, the cold heat of the evaporator 208 is used for both cooling and freezing, and the waste heat of the condenser 206 and absorber 202 is used for heating or hot water supply.
When the pressure differential between the evaporator 208 and absorber 202 becomes great in an absorption heat pump apparatus, the temperature of the absorber 202 must be lowered even more to obtain the same evaporation temperature. As a result, it is necessary to reduce the pressure loss of the evaporator 208 and absorber 202, and in general the evaporator 208, pre-cooler 209, and absorber 202 are constructed with plural parallel refrigerant flow lines as shown by the dotted lines in the figure.
However, in a conventional absorption heat pump apparatus thus comprised, the refrigerant branching into each of the parallel refrigerant flow lines is not even, and particularly in the absorber 202 branching of the refrigerant vapor and the poor solution flowing from the solution heat exchanger 203 is important, it is extremely difficult to assure uniform branching of both, and the characteristics of each heat exchanger cannot be effectively used, reducing capacity and efficiency.